Dear “Earth Talk”: Is it true that
converting crops such as corn into ethanol actually uses more energy than
is produced? — Leslie Foster, Eau Claire, Wis.
Recent revelations by University of California,
Berkeley, researcher Tad Patzek have fueled vigorous debate about the
wisdom of using fuels such as ethanol to reduce our reliance on oil and our
contribution to global warming. Patzek concluded that the production of
ethanol actually uses more energy than the resulting fuel can generate. “Ethanol production using corn grain required
29 percent more fossil energy than the ethanol fuel produced,”
reported Patzek in the journal Natural
Resources Research last winter. Ethanol
produced from other common sources, such as wood products and agricultural
waste, uses up even more fossil-fuel-derived energy. “People tend to think of ethanol and see an
endless cycle: Corn is used to produce ethanol, ethanol is burned and gives
off carbon dioxide, and corn uses the carbon dioxide as it grows,”
says Patzek, “but that isn’t the case. Fossil fuel actually
drives the whole cycle.”
Ethanol is primarily in use today as an
octane-boosting fuel additive, but it is also used as a primary fuel in
some engines. Most gasoline sold in North America today contains about 5
percent ethanol, but some vehicles — such as the Ford Explorer and
Chevy Silverado — can run on blends of as much as 85 percent ethanol.
To stimulate production, the United States offers generous tax-based
subsidies to farmers who grow crops for ethanol. Although Patzek’s evidence may be compelling,
his views on ethanol are not popular. Critics point out that his findings
are based on farming and production practices that are fast becoming
obsolete and that newer techniques and machinery can make the
ethanol-production process much more energy-efficient.
Hosein Shapouri, an economist at the U.S. Department
of Agriculture, estimates that ethanol fuel can actually generate 67
percent more energy than it takes to produce it. He points out that
scientists are
experimenting with alternative sources such as solid waste, grass, and wood
to make the ethanol production-process that much more energy-efficient.
Although the jury may still be out as to whether
ethanol production can generate a positive or negative “energy
balance,” ethanol production does hold some hazards. For instance,
the nitrogen fertilizer needed to grow corn and other crops ends up in
waterways, causing “algae blooms” that may choke out other life
in affected areas. And although ethanol produces fewer carbon monoxide
emissions than does regular gasoline, it contributes significantly to
low-lying smog. Doubts about ethanol underscore a fundamental problem
in getting many types of renewable energy sources, including hydrogen, into
mainstream use: Until fuel sources such as solar or wind power can provide
clean ways to make clean fuel, the processes must rely on coal, oil, gas,
and nuclear energy. Indeed, although we may be able to see a clean energy
future, we are still wrangling with how to get there.
For more information: U.S. Department of Energy
Ethanol Facts, www.eere.energy.gov/biomass/ethanol.html.
Send questions to “Earth Talk” in care of
E/The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; or e-mail
earthtalk@emagazine.com.
This article appears in Oct 20-26, 2005.
